Avian mycoplasmosis update

Abstract

Avian mycoplasmas occur in a variety of bird species. The most important mycoplasmas for chickens and turkeys are Mycoplasma gallisepticum (MG), M. synoviae (MS), and M. meleagridis. Besides, M. iowe (MI) is an emerging pathogen in turkeys, but of little concern for chickens. Mycoplasmas are bacteria that lack cell wall and belong to the class Mollicutes. Although they have been considered extracellular agents, scientists admit nowadays that some of them are obligatory intracellular microorganisms, whereas all other mycoplasmas are considered facultative intracellular organisms. Their pathogenic mechanism for disease include adherence to host target cells, mediation of apoptosis, innocent bystander damage to host cell due to intimate membrane contact, molecular (antigen) mimicry that may lead to tolerance, and mitotic effect for B and/or T lymphocytes, which could lead to suppressed T-cell function and/or production of cytotoxic T cell, besides mycoplasma by-products, such as hydrogen peroxide and superoxide radicals. Moreover, mycoplasma ability to stimulate macrophages, monocytes, T-helper cells and NK cells, results in the production of substances, such as tumor necrosing factor (TNF-α), interleukin (IL-1, 2, 6) and interferon (α, β, γ). The major clinical signs seen in avian mycoplasmosis are coughing, sneezing, snicks, respiratory rales, ocular and nasal discharge, decreased feed intake and egg production, increased mortality, poor hatchability, and, primarily in turkeys, swelling of the infraorbital sinus(es). Nevertheless, chronic and unapparent infections are most common and more threatening. Mycoplasmas are transmitted horizontally, from bird to bird, and vertically, from dam to offspring through the eggs. Losses attributed to mycoplasmosis, mainly MG and MS infections, result from decreased egg production and egg quality, poor hatchability (high rate of embryonic mortality and culling of day-old birds), poor feed efficiency, increase in mortality and carcass condemnations, besides medication costs. Mycoplasmas are diagnosed by serologic tests, culture and PCR and are sensitive to antimicrobials whose action sites are other than the bacterial cell wall, such as tetracyclines, macrolides, quinolones and tiamulin. However, mycoplasma control is more efficiently achieved by acquisition of birds free of MG, MS, MM and/or MI, vaccination of layers, and monitoring of breeder flocks, followed by elimination of the infected flocks that are detected.

Seroprevalence of mycoplasmosis in poultry of Bhaktapur

“…The MG infection is associated with mortality, carcass condemnation, reduced egg production, hatchability, feed efficiency and weight gain. Transmission in MG infection can be horizontal, from bird to bird, and vertical, from dam to offspring through the eggs (Nascimento et al, 2005). Some factors such as age, size of flock, location, etc., may have effect on severity of this disease (Seifi et al, 2012).…”

Mycoplasma gallisepticum como fator de risco no peso de lotes de frangos de corte com condenação por aerossaculite na Inspeção Sanitária Federal

“…Para o monitoramento sorológico, a soroaglutinação rápida em placa (SAR), a inibição da hemaglutinação (HI) e o ELISA são os testes recomendados pelos programas sanitários governamentais para os estabelecimentos avícolas, por serem menos onerosos, fáceis de desenvolver e com validade conϐirmada (Nascimento et al 2005a(Nascimento et al , 2006.…”

A comparative survey on performance of M gallisepticum-Free and M gallisepticum-infected layer flocks in Tabriz area of Iran

“…M gallisepticum (MG) is the most pathogenic and economically significant mycoplasmal pathogen of poultry. The clinical signs associated with MG infection in these avian species include respiratory rales, coughing, nasal discharge, sinusitis, and occasionally conjunctivitis (Murakami et al 2002;Nascimento et al 2005). The most prominent pathological findings include inflammatory lesions in the trachea, air sac, lungs, conjunctiva, and other tissue such as the oviduct (Nunoya et al 1995).…”